Pyloric obesity valve

ABSTRACT

The pyloric obesity valve includes a tubular valve body having proximal and distal ends. The valve body has an intermediate section which is between the proximal and distal ends. The proximal end is enlarged transversely relative to the intermediate section. The valve body has an inner surface and a lumen. The inner surface which is within the intermediate section has a cross-sectional area which is smaller than a cross-sectional area of the inner surface which coincides with the proximal end to resist a flow through the lumen of the valve body from the proximal end to the intermediate section.

FIELD OF THE INVENTION

The present invention relates generally to implants in the pylorus fortreating obesity and, more specifically, to a pyloric obesity valvewhich extends through the pylorus to delay emptying of the stomach.

BACKGROUND OF THE INVENTION

The incidence of obesity and its associated health-related problems hasbecome significant. The causes of obesity may involve a complexinterplay of genetic, environmental, psycho-behavioral, endocrine,metabolic, cultural, and socio-economic factors. Severe obesity isfrequently associated with significant comorbid medical conditions,including coronary artery disease, hypertension, type II diabetesmellitus, gallstones, nonalcoholic steatohepatitis, pulmonaryhypertension, and sleep apnea.

Current treatments for obesity range from diet, exercise, behavioralmodification, and pharmacotherapy to various types of surgery, withvarying risks and efficacy. In general, nonsurgical treatments, althoughless invasive, achieve only relatively short-term and limited weightloss in most patients. Surgical treatments include gastroplasty torestrict the capacity of the stomach to hold large amounts of food, suchas by stapling or “gastric banding”. Other surgical procedures includegastric bypass and gastric “balloons” which, when deflated, may beinserted into the stomach and then are distended by filling with salinesolution.

The need exists for low cost, less invasive interventions for thetreatment of obesity, including morbid obesity.

SUMMARY OF THE INVENTION

The pyloric obesity valve of the present invention includes a tubularvalve body having proximal and distal ends. The valve body has anintermediate section which is between the proximal and distal ends. Thevalve body is sized for implanting within the pylorus such that theproximal end is upstream and the distal end is downstream of thepylorus. The intermediate section crosses the pylorus when the valvebody is implanted within the pylorus. The proximal end is enlargedtransversely relative to the intermediate section to a dimension whichis larger than a maximum opening of the pylorus. The valve body has anentry section between the intermediate section and proximal end. Theentry section has an outer surface which is shaped such that, when thevalve body is implanted within the pylorus, the outer surface is thensubstantially in direct contact with an inner surface of the stomachwhich is adjacent to the pylorus. The valve body has an inner surfaceand a lumen. The lumen has a transverse boundary which is defined by theinner surface of the valve body. The inner surface which is within theintermediate section has a cross-sectional area which is smaller than across-sectional area of the inner surface which coincides with theproximal end to resist a flow through the lumen of the valve body fromthe proximal end to the intermediate section.

The pyloric obesity valve, when implanted so to extend through thepylorus, obstructs and impedes the passage of chyme from the stomachthrough the pylorus into the duodenum. Chyme is the partially digestedfood which flows into the duodenum from the stomach. The duodenum is thelongitudinal portion of the small intestine which contains the proximalend thereof. The obstruction and impediment provided by the pyloricobesity valve delays the emptying of the chyme in the stomach throughthe pylorus into the duodenum. Delaying this emptying of the stomachwill typically prolong the satiation of the patient which results fromthe chyme in the stomach. Consequently, the onset of hunger whichnormally results from the stomach being empty of chyme is delayed. Theintake of food by the patient which results from hunger is consequentlydelayed. Absent some other reason for eating, the patient will normallyexperience longer time periods between eating which will typicallyresult in a reduction in the daily food absorption by the patient. Thelonger durations between eating would not appear to result in thepatient desiring larger quantities of food when the hunger returns.Consequently, the longer durations between eating should contribute tosignificant weight loss in the patient.

These and other features of the invention will be more fully understoodfrom the following description of specific embodiments of the inventiontaken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an anatomical elevational view of a pylorus and the adjacentportions of the stomach and duodenum, the walls of the pylorus, stomachand duodenum being broken away to show a pyloric obesity valve inaccordance with the present invention;

FIG. 2 is an elevational side view of the pyloric obesity valve of FIG.1, the pyloric obesity valve being shown as removed from the alimentarycanal and as having a stent in the valve body;

FIG. 3 is an elevational side view of an alternative embodiment of thepyloric obesity valve of FIG. 1, the pyloric obesity valve being shownas removed from the alimentary canal and as having stents in the entryand discharge sections;

FIG. 4 is longitudinal cross-sectional view of a further alternativeembodiment of the pyloric obesity valve of FIG. 1, the pyloric obesityvalve being shown as removed from the alimentary canal and as havingtransverse baffles secured within the valve body;

FIG. 5 is a transverse cross-sectional view of the pyloric obesity valvein the plane indicated by line 5-5 of FIG. 4, the baffles being shown aslongitudinally and transversely offset relative to the valve body;

FIG. 6 is a longitudinal cross-sectional view of a further alternativeembodiment of the pyloric obesity valve of FIG. 1, the pyloric obesityvalve being shown as removed from the alimentary canal and as havingtransverse membranes secured within the valve body;

FIG. 7 is a transverse cross-sectional view of the pyloric obesity valvein the plane indicated by line 7-7 of FIG. 6, one of the membranes beingshown as having slits therein;

FIG. 8 is a longitudinal cross-sectional view of a further alternativeembodiment of the pyloric obesity valve of FIG. 1, the pyloric obesityvalve being shown as removed from the alimentary canal and as having aninternal thread on the inner surface of the valve body;

FIG. 9 is a transverse cross-sectional view of the pyloric obesity valvein the plane indicated by line 9-9 of FIG. 8, the internal thread beingshown as transversely overlapping; and

FIG. 10 is an elevational side view of a further alternative embodimentof the pyloric obesity valve of FIG. 1, the pyloric obesity valve beingshown as removed from the alimentary canal and as having longitudinaland transverse supports on the valve body.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings and more particularly to FIG. 1, a centralportion of the alimentary canal 10 in which the pyloric obesity valve 12is located is illustrated. This portion of the alimentary canal 10includes the stomach 15 and duodenum 17. The stomach 15 has lesser andgreater curves 20, 22, and a pyloric canal 25 which has an inner surface26. The pyloric canal 25 leads to the duodenal bulb 16 of the duodenum17 by way of the pylorus 27, which may be referred to alternatively asthe gastric outlet or pyloric opening. The pylorus 27 forms the distalaperture of the stomach 15 and has an enclosing circular layer of musclewhich is normally contracted to close the aperture but which relaxes toprovide an open but restrictive passage. Although subject to substantialvariation in different individuals, the pylorus 27 has a maximum opendiameter of about 2 cm. and the duodenum 17 has a diameter whichtypically is about 18 to 20 mm. in a representative patient. The chyme30 passes from the pyloric canal 25 through the pylorus 27 into theduodenal bulb 16 of the duodenum 17. The duodenum 17, including theduodenal bulb 16, is the proximate segment of the small intestine. Theduodenal bulb 16 has an inner surface 31.

The pyloric obesity valve 12 is located within the pyloric canal 25,pylorus 27, and duodenal bulb 16, as shown in FIG. 1. The pyloricobesity valve 12 is shown in FIG. 2 before insertion into the pyloriccanal 25, pylorus 27, and duodenal bulb 16. The pyloric obesity valve 12includes a valve body 32 which has outer and inner surfaces 35, 37. Theinner surface 37 defines a transverse boundary of a lumen 40 of thevalve body 32. The valve body 32 has proximal and distal ends 42, 45 andan intermediate section 47 which is between the proximal and distalends. The intermediate section 47 has an outer surface 48 whichcoincides with a longitudinal portion of the outer surface 35. The valvebody 32 has an entry section 50 between the intermediate section 47 andproximal end 42. The entry section 50 has an outer surface 60 whichcoincides with a longitudinal portion of the outer surface 35. The valvebody 32 has a discharge section 52 between the intermediate section 47and distal end 45. The discharge section 52 has an outer surface 67which coincides with a longitudinal portion of the outer surface 35.

The proximal and distal ends 42, 45 are enlarged transversely relativeto the intermediate section 47. The cross-sections of the entry anddischarge sections 50, 52 increase in size with increasing longitudinalseparation from the intermediate section 47. In an alternativeembodiment, it is possible for a longitudinal portion of the entrysection 50 to have a constant cross-section. Also, in alternativeembodiments, it is possible for a longitudinal portion or the entirelength of the discharge section 52 to have a constant cross-section.Additionally, in an alternative embodiment, the cross-section of thedistal end 45 may be the same as the cross-section of the intermediatesection 47. The valve body 32 typically has an annular cross-section.Alternative embodiments of the pyloric obesity valve 12 are possible inwhich the valve body 32 has a non-annular cross-section, such as thecross-section of the valve body 32 as manufactured being elliptical orhaving multiple radii with different angular positions within the valvebody.

The valve body 32 includes a tubular stent 55 which has a plurality ofelongate structural members 57. The structural members 57 are arrangedin a crossing pattern. The structural members 57 may be wires, thecross-sections of which may be round, rectangular, square or numerousother geometric shapes.

The stent 55, including the structural members 57, may be formed ofmaterials such as nitinol, elgiloy, stainless steel or cobalt chromium,including NP35N. Additionally, the stent 55, including the structuralmembers 57, may be formed of materials such as stainless steel,platinum, gold, titanium and other biocompatible metals, as well aspolymeric stents. Polymeric stents may be provided, such as POLYFLEX®stents which are made by the Boston Scientific Corporation. Also, thestent 55, including the structural members 57, may be formed ofmaterials including cobalt-based alloy such as Elgiloy, platinum, gold,titanium, tantalum, niobium, and combinations thereof and otherbiocompatible materials, as well as polymers. The stent 55, includingthe structural members 57, may be formed of any biocompatible polymerincluding, but not limited to, PET, PTFE, PE, and nylon. Also, the stent55, including the structural members 57, may be formed of biocompatibleceramics, such as structurally or as coatings. Additionally, thestructural members 57 which have an inner core formed of tantalum gold,platinum, iridium, or a combination thereof, and an outer cladding ofnitinol to provide composite members for improved radio-opacity orvisibility. Examples of such composite members are disclosed in U.S.Patent Application Publication No. 2002/0035396, the entire contents ofwhich are hereby incorporated by reference herein. The structuralmembers 57 may be formed of combinations of more than one metal, morethan one polymer, and metals and polymers.

The stent 55 may have various embodiments. For example, the stent 55 maybe self-expanding or expandable by a balloon. The stent 55 may includeone or more coiled stainless steel springs, helically wound coil springsincluding a heat-sensitive material, or expanding stainless steel stentsformed of stainless steel wire in a zig-zag pattern. The stent 55 may bemade with braided, woven, knitted or otherwise twisted filaments. Thestent 55 may include joined filaments which may be joined by welding,soldering, adhesives and the like. The stent 55 may be formed from atube which is cut mechanically or by lasers and the like. The stent 55may be molded, spun, or created in layers (lithography) especially ifpolymeric. The stent 55 may be capable of radially contracting orexpanding, such as by radial or circumferential distension ordeformation. The stent 55 may be self-expanding, such as a stent whichis mechanically urged to radially expand, and a stent which expands atone or more specific temperatures as a result of the memory propertiesof the stent material for a specific configuration. Such a stent 55 mayinclude nitinol material for providing radial expansion thereof both bymechanical urging, or by the memory properties of the nitinol based onone or more specific temperatures. The stent 55 may have any shapememory material including metals and polymers. The stent 55 may includeone or more of the stents disclosed in U.S. Pat. Nos. 4,503,569,4,733,665, 4,856,516, 4,580,568, 4,732,152, and 4,886,062, the entirecontents of each of which are hereby incorporated by reference herein.

The pyloric obesity valve 12 may include a tubular cover which issecured to the outer surface of the stent 55. The cover may be formed ofvarious biocompatible materials. For example, the cover may be aPERMALUME® covering which is secured to the stent 55, which is a stentconstituted by the WALLSTENT® RX Biliary Endoprosthesis, both of whichare made by the Boston Scientific Corporation. The PERMALUME® coveringis formed of polyurethane. Alternatively, the cover may be formed ofexpanded polytetrafluoroethylene (ePTFE). The cover, and possibly thestent 55, may be an elastomer such as silicone, c-flex, polyurethane,PEBAX® copolymer, or other known biocompatible materials. The covercould be made of the PERMALUME® material which is used in combinationwith the WALLSTENT®. The cover may have other materials andconfigurations. For example, the longitudinal center and end portions ofthe cover may be an elastomer with a shore hardness of 10 to 100 ShoreA. The shore hardness of the elastomer of the longitudinal center andend portions of the cover may also be specified in the shore D scale.The center portion is softer and able to close with the sphincterpressure of the pylorus 27 while the relatively harder end portionsbetter retain the shape thereof to match the anatomical pockets. Thestent 55 and a cover may be attached to one another by variousprocesses, depending upon the materials of the cover and stent. Forexample, a cover may be insert molded over the stent 55, which may alsobe formed of a polymeric elastomer or silicone. Alternatively, the coverand stent 55 may be secured to one another by an interference fitbetween the two structures. Alternatively, a shorter term implant may beprovided by a coating on the outer surface of the stent 55 to facilitateremoval thereof from the tissue. The cover may be added to the stent 55by dipping the stent in a liquid polymer. Alternatively, the covermaterial may be sprayed on, or molded onto the stent 55. In a furtheralternative embodiment, the cover may be wrapped around, woven on, spunaround, knitted on, and adhesed to the stent 55. A further alternativeembodiment provides for the implantation of the stent 55 which does nothave a cover on the outer surface thereof to facilitate tissue in-growthor adhesions for a more permanent implant.

In alternative embodiments, the valve body 32 may be a polymer sleeve.The valve body 32 may be formed of biocompatible materials, such aspolymers which may include fillers such as metals, carbon fibers, glassfibers or ceramics. Such polymers may include olefin polymers,polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylenewhich is not expanded, fluorinated ethylene propylene copolymer,polyvinyl acetate, polystyrene, poly(ethylene terephthalate),naphthalene dicarboxylate derivatives, such as polyethylene naphthalate,polybutylene naphthalate, polytrimethylene naphthalate andtrimethylenediol naphthalate, polyurethane, polyurea, silicone rubbers,polyamides, polycarbonates, polyaldehydes, natural rubbers, polyestercopolymers, styrene-butadiene copolymers, polyethers, such as fully orpartially halogenated polyethers, copolymers, and combinations thereof.Also, polyesters, including polyethylene terephthalate (PET) polyesters,polypropylenes, polyethylenes, polyurethanes, polyolefins, polyvinyls,polymethylacetates, polyamides, naphthalane dicarboxylene derivatives,and natural silk may be included in the valve body 32.

The valve body 32 may be treated with anti-thrombogenic agents (such asheparin, heparin derivatives, urokinase, and PPack (dextrophenylalanineproline arginine chloromethylketone)), anti-proliferative agents (suchas enoxaprin, angiopeptin, or monoclonal antibodies capable of blockingsmooth muscle cell proliferation, hirudin, and acetylsalicylic acid),anti-inflammatory agents (such as dexamethasone, prednisolone,corticosterone, budesonide, estrogen, sulfasalazine, and mesalamine),antineoplastic/antiproliferative/anti-miotic agents (such as paclitaxel,5-fluorouracil, cisplatin, vinblastine, vincristine, epothilones,endostatin, angiostatin and thymidine kinase inhibitors), anestheticagents (such as lidocaine, bupivacaine, and ropivacaine),anti-coagulants (such as D-Phe-Pro-Arg chloromethyl keton, an RGDpeptide-containing compound, heparin, antithrombin compounds, plateletreceptor antagonists, anti-thrombin antibodies, anti-platelet receptorantibodies, aspirin, prostaglandin inhibitors, platelet inhibitors andtick antiplatelet peptides), vascular cell growth promotors (such asgrowth factor inhibitors, growth factor receptor antagonists,transcriptional activators, and translational promotors), vascular cellgrowth inhibitors (such as growth factor inhibitors, growth factorreceptor antagonists, transcriptional repressors, translationalrepressors, replication inhibitors, inhibitory antibodies, antibodiesdirected against growth factors, bifunctional molecules consisting of agrowth factor and a cytotoxin, bifunctional molecules consisting of anantibody and a cytotoxin), cholesterol-lowering agents, vasodilatingagents, and agents which interfere with endogenous vascoactivemechanisms. The valve body 32 may be treated with agents which areparticular to digestion or to promote sphincter activity.

The valve body 32 has a cross-section which varies relative to thelongitudinal axis thereof. This is a result of the proximal and distalends 42, 45 being enlarged relative to the intermediate section 47 andthe tapering of the cross-sections of the entry and discharge sections50, 52 between the proximal and distal ends, respectively, and theintermediate section. The reduced cross-section of the intermediatesection 47 provides for a narrowing of the longitudinal portion of thelumen 40 therein. This narrowing of the lumen 40 provides resistance tothe flow of the chyme 30 therein from the proximal end 42 to theintermediate section 47. The distal end 45 may be enlarged transverselyto a lesser degree relative to the proximal end 42, as shown in FIGS. 1and 2. In an alternative embodiment of the valve body 32, the distal end45 may be enlarged transversely to different degrees relative to thedegree of transverse enlargement shown in FIGS. 1 and 2. In a furtheralternative embodiment of the valve body 32, the distal end 45 may havegenerally the same transverse dimension as the intermediate section 47.

The valve body 32 is sized for implanting within the pylorus 27 byinserting the distal end 45 in a downstream direction through thepylorus. Such insertion provides for the proximal end 42 to be upstreamand the distal end 45 to be downstream of the pylorus 27, as shown inFIG. 1. The insertion of the distal end 45 through the pylorus 27results in the outer surface 48 of the intermediate section 47 crossingthe pylorus. Also, the intermediate section 47 may be in direct contactwith the pylorus 27. The outer surface 60 of the entry section 50 ispreferably shaped such that, when the valve body 32 is implanted withinthe pylorus 27, the outer surface 60 is in substantially direct contactwith the inner surface 26 of the pyloric canal 25 of the stomach 15which is adjacent to the pylorus. The inner surface 26 is adjacent tothe pylorus 27. The outer surface 60 of the entry section 50 is heldagainst the inner surface 26 by the stent 55. The shape of the outersurface 35 before insertion of the valve body 32 into the pyloric canal25, pylorus 27, and duodenal bulb 16, as shown in FIG. 2, may bedifferent from the shape of the outer surface 35 after the insertion ofthe valve body 32, as shown in FIG. 1. This may be provided by thecross-section of the outer surface 35 being larger than thecorresponding cross-sections of the pyloric canal 25, pylorus 27, andduodenal bulb 16 before the insertion of the valve body 32 therein, andthe valve body being formed of a compressible material. Consequently,insertion of the valve body 32 into the pyloric canal 25, pylorus 27,and duodenal bulb 16 results in radial compression of the valve bodysuch that the outer surface 35 is urged by the radial expansion of thevalve body into direct contact with the anatomy of the pyloric canal 25,pylorus 27, and duodenal bulb 16, as shown in FIG. 1. The direct contactbetween the valve body 32 and the anatomy of the pyloric canal 25,pylorus 27, and duodenal bulb 16 may be facilitated by the increasedcross-sections of the entry and discharge sections 50, 52 relative tothe intermediate section 47 and, in some anatomies, by the valve bodyhaving a non-annular cross-section.

In an alternative embodiment, the respective cross-sections of theintermediate and discharge sections 47, 52 may be the same to provide aradial clearance between the discharge section and duodenal bulb 16.

The transverse enlargements of the proximal end 42 and entry section 50are greater than the maximum transverse opening of the pylorus 27. Theseenlargements provide resistance to downstream displacement of the valvebody 32 relative to the pylorus 27 to maintain the valve body therein.The lumen 40 and the substantially direct contact of the outer surface60 with the inner surface 26 results in the chyme 30 which is in thepyloric canal 25 flowing through the lumen 40 into the duodenal bulb 16of duodenum 17. The substantially direct contact of the outer surface 60with the inner surface 26 also prevents the chyme 30 from being trappedbetween the surfaces 26, 60 and possibly leaking through the surface 26.The direction of the flow of the chyme 30 through the lumen 40 and thenarrowing thereof within the intermediate section 47 forces the entrysection 50 against the inner surface 26 to resist upstream displacementof the valve body 32 relative to the pylorus 27 to maintain the valvebody therein.

The implantation provided by the forcing of the entry section 50 againstthe inner surface 26 as a result of the flow of the chyme 30 through thelumen 40 provides sufficient resistance to downstream displacement ofthe valve body 32 relative to the pylorus 27 to maintain the valve bodytherein. This allows for the variations in the transverse dimensions ofthe distal end 45 and discharge section 52. These variations arepossible since the distal end 45 and discharge section 52 are notrequired to implant the valve body 32 within the pylorus 27. Theimplantation of the pyloric obesity valve 12 results in the outersurface 48 of the intermediate section 47 being in direct contact withthe pylorus 27. The insertion of the valve body 32 through the pylorus27 in the distal direction results in the outer surface 67 of thedischarge section 52 being adjacent to the inner surface 31 of theduodenal bulb 16 of the duodenum 17, as shown in FIG. 1. The innersurface 31 is adjacent to the pylorus 27. Preferably, the outer surface67 is in direct contact with the inner surface 31, as shown in FIG. 1.Alternative embodiments of the valve body 32 are possible in which atransverse clearance is provided between the outer and inner surfaces67, 31.

The pyloric obesity valve 12 may be dislodged from the implantationthereof in the pyloric canal 25, pylorus 27 and duodenal bulb 16 bydisplacing the valve body 32 in an upstream direction relative to thepylorus. The displacement of the valve body 32 in the upstream directionis sufficient to retract the intermediate section 47 from within thepylorus 27.

An alternative embodiment of the pyloric obesity valve 12 a is shown inFIG. 3. Parts illustrated in FIG. 3 which correspond to partsillustrated in FIGS. 1 and 2 have, in FIG. 3, the same reference numeralas in FIGS. 1 and 2 with the addition of the suffix “a”. In thisalternative embodiment, the entry and discharge sections 50 a, 52 a ofthe valve body 32 a each include corresponding tubular stents 68, 69.The stents 68, 69 may have structures which correspond to the stent 55.The intermediate section 47a does not include a stent. Consequently, theentry and discharge sections 50 a, 52 a are stiffer transverselyrelative to the transverse flexibility of the intermediate section 47 a.

The pyloric obesity valve 12 a has an anchor structure 62 which includesa pair of hooks 65 which are attached to the outer surface 60 a of theentry section 50 a, as shown in FIG. 2. The hooks 65 have longitudinalpositions relative to the valve body 32 a which are adjacent to theproximal end 42 a. The hooks 65 have opposing transverse positionsrelative to the valve body 32 a. The hooks 65 each have a distalcurvature relative to the valve body 32 a such that the ends thereofpoint in a generally distal direction. Alternative embodiments of theanchor structure 62 are possible which include different numbers of thehooks 65 and attachment thereof to different locations on the outersurface 35 a of the valve body 32 a. For example, a hook 65 may beattached to the distal end 45 a, as shown in FIG. 3. Alternativeembodiments of the anchor structure 62 are possible which include morethan one hook 65 each of which is attached to the valve body 32 aadjacent to the distal end 45 a. In such alternative embodiments of theanchor structure 62, the hooks 65 preferably have a distal curvaturerelative to the valve body 32 a, although other directions of curvatureof the hooks 65 are possible.

The anchor structure 62 includes a stake 70 which is attached to theouter surface 67 a of the discharge section 52 a, as shown in FIG. 3.The stake 70 has a longitudinal position relative to the valve body 32 awhich is adjacent to the distal end 45 a. The stake 70 may have opposingtransverse positions relative to the valve body 32 a. The stake 70 has adistal inclination relative to the valve body 32 a. The stake 70 may bestraight, as shown in FIG. 3, or, in an alternative embodiment, curved.Alternative embodiments of the anchor structure 62 are possible whichinclude more than one stake 70 each of which has a longitudinal positionrelative to the valve body 32 a which is adjacent to the distal end 45a. Alternative embodiments of the anchor structure 62 are possible whichinclude different numbers of the stakes 70 and attachment thereof todifferent locations on the outer surface 35 a of the valve body 32 a. Insuch alternative embodiments of the anchor structure 62, the stakes 70preferably have a distal inclination relative to the valve body 32 a,although other inclinations of the stakes 70 are possible. Alternativeembodiments of the anchor structure 62 may have only hooks 65, onlystakes 70, neither or both.

The hooks 65 and stakes 70 resist migration of the valve body 32 a inthe distal direction relative to the pyloric canal 25, pylorus 27, andduodenal bulb 16. This resistance results from the distal direction ofthe peristalsis relative to the pyloric canal 25, pylorus 27, andduodenal bulb 16.

During implantation of the pyloric obesity valve 12 a including theinsertion of the valve body 32 a through the pylorus 27 in thedownstream direction, the direct contact of the outer surface 60 a withthe inner surface 26 of the pyloric canal 25 results in the hooks 65being implanted in the inner surface 26. Such implantation also resultsin the stakes 70 being implanted in the inner surface 31 of the duodenalbulb 16 of the duodenum 17.

The distal curvature of the hooks 65 and distal inclination of thestakes 70 facilitate the implantation thereof in the inner surfaces 26,31, respectively, as a result of the insertion of the valve body 32 athrough the pylorus 27 in the downstream direction. Such displacement ofthe valve body 32 a in the downstream direction may be the result of aninitial insertion of the pyloric obesity valve 12 a through the mouth ofthe patient. Such oral insertion of the pyloric obesity valve 12 a maybe advantageous by not requiring a surgical incision, such as throughthe abdomen, for implantation of the pyloric obesity valve.

The implantation of the pyloric obesity valve 12 a results in the outersurface 48 a of the intermediate section 47 a being in direct contactwith the pylorus 27. The increased flexibility of the intermediatesection 47 a relative to the entry and discharge sections 50 a, 52 aprovides for the conformance thereof to the pylorus 27 duringcontraction and dilation thereof which may occur as a natural result ofdigestion.

The dislodging of the pyloric obesity valve 12 a including theretraction of the valve body 32 a through the pylorus 27 in the upstreamdirection is sufficient to dislodge the hooks 65 from the inner surface26 of the pyloric canal 25 of the stomach 15. Such displacement furtherprovides for the stakes 70 to be dislodged from the inner surface 31 ofthe duodenal bulb 16 of the duodenum 17. The distal curvature of thehooks 65 and the distal inclination of the stake 70, facilitatedislodging thereof from the inner surfaces 26, 31, respectively, bydisplacement of the valve body 32 a in the upstream direction relativeto the pylorus 27.

The dislodging of the pyloric obesity valve 12 a from the implantationthereof by displacement of the valve body 32 a in the upstream directionmay ultimately result in the removal of the pyloric obesity valvethrough the mouth of the patient. Such oral removal of the pyloricobesity valve 12 a may be advantageous by not requiring a surgicalincision, such as through the abdomen, for dislodging the implantationof the pyloric obesity valve.

An alternative embodiment of the pyloric obesity valve 12 b is shown inFIGS. 4 and 5. Parts illustrated in FIGS. 4 and 5 which correspond toparts illustrated in FIGS. 1 and 2 have, in FIGS. 4 and 5, the samereference numeral as in FIGS. 1 and 2 with the addition of the suffix“b”. In this alternative embodiment, a flow restrictor 72 is secured tothe inner surface 37 b of the valve body 32 b. The flow restrictor 72includes baffles 75, 77, 79, 81, 83, 85, 87, each of which is secured tothe inner surface 37 b of the valve body 32 b. As shown in FIG. 4, thebaffles 75, 77, 79, 81, 83, 85, 87 are within the intermediate section47 b. The baffles 75, 77, 79, 81, 83, 85, 87 are formed of acompressible material which conforms to the periodically reducedtransverse dimension of the pylorus 27. This periodically reducedtransverse dimension typically results from the contraction of thesphincter in the pylorus 27 during peristalsis.

In an alternative embodiment of the flow restrictor 72, the baffles 75,77, 79, 81, 83, 85, 87 may be within the entry and discharge sections 50b, 52 b, and fewer or no baffles in the intermediate section 47 b. Apossible advantage of such an embodiment is that the degree ofcompression required of the baffles 75, 77, 79, 81, 83, 85, 87 in theentry and discharge sections 50 b, 52 b is less than the degree ofcompression which is typically required of the baffles which are locatedin the intermediate section 47 b. This results from the longitudinaloffset of the entry and discharge sections 50 b, 52 b relative to thepylorus 27. The longitudinal offset reduces the possible transversecontraction of the entry and discharge sections 50 b, 52 b which mayresult from the contraction of the sphincter in the pylorus 27.

The baffles 75, 77, 79, 81, 83, 85, 87 are longitudinally offsetrelative to the valve body 32 b such that the baffles are eachlongitudinally separated from the adjacent baffles, as shown in FIG. 4.The baffles 75, 77, 79, 81 are secured to sections of the inner surface37 b of the valve body 32 b which are transversely offset relativethereto. Consequently, the sections of the inner surface 37 b to whichadjacent baffles, such as the baffles 75, 77, are secured aretransversely offset relative to the valve body 32 b, as shown in FIG. 5.The baffles 83, 85, 87 are secured to sections of the inner surface 37 bwhich correspond transversely to the sections of the inner surface 37 bto which are connected the baffles 75, 77, 79. Consequently, the baffles83, 85, 87 are offset transversely relative to the valve body 32 b.

The baffles 75, 77, 79, 81, 83, 85, 87 are sized and secured to asection of the inner surface 37 b such that a transverse clearance isprovided between each baffle and the inner surface 37 b. Consequently,the chyme 30 may flow longitudinally between each of the baffles 75, 77,79, 81, 83, 85, 87 and the longitudinally corresponding portions of theinner surface 37 b. Such flow of the chyme 30 is resisted by the baffles75, 77, 79, 81, 83, 85, 87 as a result of the reduction in thetransverse area through which the chyme may flow resulting from thesurface area of the baffles. Additional resistance to the flow of thechyme 30 is provided by the transverse offset of the baffles 75, 77, 79,81, 83, 85, 87 which requires the chyme to flow in a serpentinedirection as a result of the transverse offset of the attachments of thebaffles to the inner surface 37 b. Alternative embodiments of the flowrestrictor 72 are possible which have different numbers of baffles, suchas the baffles 75, 77, 79, 81, 83, 85, 87. Further alternativeembodiments of the flow restrictor 72 are possible which have structuresfor resisting the flow of the chyme 30 within the lumen 40 b where suchstructures are different from the baffles 75, 77, 79, 81, 83, 85, 87.Further alternative embodiments of the pyloric obesity valve 12 b arepossible which have more than a single flow restrictor 72.

An alternative embodiment of the pyloric obesity valve 12 b is shown inFIGS. 6 and 7. Parts illustrated in FIGS. 6 and 7 which correspond toparts illustrated in FIGS. 1 and 2 have, in FIGS. 6 and 7, the samereference numeral as in FIGS. 1 and 2 with the addition of the suffix“c”. In this alternative embodiment, a flow restrictor 89 is secured tothe inner surface 37 c of the valve body 32 c. The flow restrictor 72 cmay include the transverse membranes 90, 92, 94, 96 each of which has aperiphery the entire length of which is secured to the inner surface 37c of the valve body 32 c. The membranes 90, 92, 94, 96 are eachsubstantially impermeable. Alternative embodiments of the flowrestrictor 89 are possible which have one or more membranes, such as themembranes 90, 92, 94, 96.

The membrane 90 has an inner section 99 which is circular and containedwithin an outer section 101. The outer section 101 is annular and has anouter peripheral which is secured to the inner surface 37 c. The innerand outer sections 99, 101 are each flexible longitudinally relative tothe valve body 32 c. The longitudinal flexibility of the inner section99 is greater than the longitudinal flexibility of the outer section101. Consequently, the application of a uniform longitudinal force tothe inner and outer sections 99, 101 will produce a longitudinaldeflection of the inner section which is greater than the longitudinaldeflection of the outer section. The respective longitudinalflexibilities of the inner and outer sections 99, 101 may be provided bythe thickness of the inner section being smaller than the thickness ofthe outer section. The thicknesses of the inner and outer sections 99,101 may be uniform in the transverse direction. Alternatively, thethicknesses of the inner and outer sections 99, 101 may vary in thetransverse direction to provide tapered thicknesses thereof. In analternative embodiment of the flow restrictor 89, the membranes 90, 92,94, 96 may each be substantially inflexible longitudinally relative tothe valve body 32 c.

The flow restrictor 89 includes one or more orifices which, in thepyloric obesity valve 12 c shown in FIG. 7, are provided by horizontaland vertical slits 103, 105. The horizontal and vertical slits 103, 105intersect with one another at a location which coincides with the centerof the inner section 99. The membranes 92, 94, 96 each have one or moreorifices formed therein. The orifices in the membranes 92, 94, 96 may beprovided by slits corresponding to the horizontal and vertical slits103, 105. Alternatively, the orifices of the membranes 92, 94, 96 mayhave configurations which differ from the horizontal and vertical slits103, 105. Alternative embodiments of the orifices in the membranes 90,92, 94, 96 may be provided by a small hole, a slit, a slot, a cross,such as the horizontal and vertical slits 103, 105, or any combinationthereof.

The membranes 90, 92, 94, 96 and the corresponding orifices thereinprovide resistance to the flow of the chyme 30 through the lumen 40 c byrequiring the chyme to flow through the relatively small cross-sectionalareas of the orifices. This resistance to the flow of the chyme 30 maybe controllably adjusted such as by varying the longitudinal flexibilityof the section of the membrane in which the one or more orifices areformed. A reduction in the resistance to the flow of the chyme 30 may,for example, be provided by increasing the longitudinal flexibility ofthe inner section 99. Increasing the longitudinal flexibility of theinner section 99 will reduce the longitudinal force required tolongitudinally deflect the portions of the inner section which arecontiguous with the horizontal and vertical slits 103, 105. Longitudinaldeflection of these portions of the inner section 99 typically increasesthe cross-sectional area of the horizontal and vertical slits 103, 105which reduce the resistance provided by the membrane 90 to the flow ofthe chyme 30. Conversely, decreasing the longitudinal flexibility of theinner section 99 will typically increase the resistance to the flow ofthe chyme 30 which is provided by the membrane 90. In alternativeembodiments, the membranes 90, 92, 94, 96 can be configured to promoteor restrict flow through the lumen 40 c. The membranes 90, 92, 94, 96may have a uniform thickness or tapered thickness, may be rounded, ormay have other profiles. The membranes 90, 92, 94, 96 may have differentcharacteristics relative to one another.

An alternative embodiment of the pyloric obesity valve 12 d is shown inFIG. 8. Parts illustrated in FIG. 8 which correspond to partsillustrated in FIGS. 1 and 2 have, in FIG. 8, the same reference numeralas in FIGS. 1 and 2 with the addition of the suffix “d”. In thisalternative embodiment, a flow restrictor 107 is secured to the innersurface 37 d of the valve body 32 d. The flow restrictor 107 includes aninternal thread 108 having rotational and longitudinal orientationswhich are offset relative to the valve body 32 d. These offsetrotational and longitudinal orientations provide for the internal thread108 to be helical in a valve body 32 d which has an annularcross-section, as shown in FIG. 8. The internal thread 108 has asufficiently large transverse dimension such that an internal edge 110thereof has longitudinal portions which transversely overlap one anotherrelative to the valve body 32 d. This transverse overlap results in thepassage through the longitudinal portion of the lumen 40 d, within whichthe internal thread 108 is located, being substantially limited to achannel 112 within the internal thread 108. The configuration of theinternal thread 108 has similarities to an auger in that material, suchas the chyme 30, is displaced longitudinally through the channel 112.The formation of the internal thread 108 on the inner surface 37dprovides the flow restrictor 107 with a correspondence to an internalauger. In alternative embodiments of the pyloric obesity valve 12 d, theflow restrictor 107 may have more than one of the internal threads 108.In a further alternative embodiment of the pyloric obesity valve 12 d,the internal thread 108 may have a sufficiently limited transversedimension to provide a transverse clearance between the internal edge110 such that the longitudinal portions of the internal edge 110 do nottransversely overlap one another relative to the valve body 32 d. Thetransverse dimension of the internal thread 108 is sufficient to resistthe flow of the chyme 30 through the lumen 40 d.

An alternative embodiment of the pyloric obesity valve 12 e is shown inFIG. 10. Parts illustrated in FIG. 10 which correspond to partsillustrated in FIGS. 1 and 2 have, in FIG. 10, the same referencenumeral as in FIGS. 1 and 2 with the addition of the suffix “e”. In thisalternative embodiment, the pyloric obesity valve 12 e includes anelongate transverse support member 115 which is secured to the entrysection 50 e in adjacent relation to the proximal end 42 e. The supportmember 115 may be circular for attachment to the outer surface 60 ewhich has a cross-section which is circular. The support member 115 iscontinuous. In an alternative embodiment of the pyloric obesity valve 12e, the support member 115 may include arcuate sections the ends of whichmay abut one another or be transversely offset from one another. Also,such arcuate sections of the support member 115 may be longitudinallyoffset from one another. In a further alternative embodiment of thepyloric obesity valve 12 e, more than one support member 115 may besecured to the entry section 50 e.

The pyloric obesity valve 12 e includes elongate longitudinal supportmembers 117 which are secured to the discharge section 52 e and whichare transversely offset relative to one another by generally equaldimensions. The support members 117 are continuous. In an alternativeembodiment of the pyloric obesity valve 12 e, the support members 117may include longitudinal sections the ends of which may abut one anotheror be longitudinally offset from one another. In further alternativeembodiments of the pyloric obesity valve 12 e, different numbers of thesupport members 117, including a single one thereof, may be secured tothe discharge section 52 e.

Alternative embodiments of the pyloric obesity valve 12 e are possiblein which one or more transverse support members 115 are secured to thedischarge section 52 e and one or more longitudinal support members 117are secured to the entry section 50 e. In further alternativeembodiments of the pyloric obesity valve 12 e, the transverse andlongitudinal support members 115, 117 may both be secured to the entrysection 50 e. Also, the transverse and longitudinal support members 115,117 may both be secured to the discharge section 52 e. Additionally, thetransverse and longitudinal support members 115, 117 may be located ateither or both of the proximal and distal ends 42 e, 45 e.

Alternative embodiments of the pyloric obesity valve 12 e are possiblewhich include one or more support structures secured to the entrysection 50 e which maintain the entry section in an open configurationto allow the flow of the chyme 30 through the proximal end 42 e into thelumen 40 e. Resistance to the flow of the chyme 30 through the lumen 40e is provided by the reduction in the cross-section of the portion ofthe lumen which is within the intermediate section 47 e relative to thecross-section of the portion of the lumen which is within the entrysection 50 e. This reduction in the respective cross-sections may beprovided by a taper between the entry and intermediate sections 50 e, 47e. The one or more support structures which are secured to the entrysection 50 e allows the entry section and intermediate section 47 e tobe formed of flexible material, such as a membrane, since the entrysection is held in an open configuration by the one or more supportstructures. Such an assembly may resemble a windsock which is held openat the top thereof. The one or more support structures which are securedto the entry section 50 e may be provided by struts which are inclinedrelative to the longitudinal axis of the valve body 32 e, a stent, astent component, or a transverse support member 115 which is defined bya metal or material hoop. The entry section 50 e to which the one ormore support structures are secured may be included in a valve body 32 ehaving an intermediate section 47 e which is flexible and does not havea stent secured thereto. Such a valve body 32 e may have a dischargesection 52 e which has an enlarged cross-section relative to thecross-section of the intermediate section 47 e and a taper whichcorresponds to the taper of the entry section 50 e except for thelongitudinal inclination thereof which is the mirror-image of thelongitudinal inclination of the taper of the entry section 50 e. A stentmay be secured to the discharge section 52 e. The valve body 32 e inthese alternative embodiments may be a molded tube, and may includeinner flow restrictions, such as the flow restrictor 72 e.

An alternative embodiment of the pyloric obesity valve 12 is a valvestructure for implanting in or around a sphincter in a body lumen. Anexample of such a body lumen is the pyloric canal 25, and the lumens inthe pylorus 27 and duodenal bulb 16 in fluid communication therewith.The corresponding sphincter for this body lumen is the pylorus 27. Otherbody lumens have corresponding sphincters, in or around which the valvestructure may be implanted for restricting the flow rate of fluidswithin the body lumens.

While the invention has been described by reference to certain preferredembodiments, it should be understood that numerous changes could be madewithin the spirit and scope of the inventive concept described.Accordingly, it is intended that the invention not be limited to thedisclosed embodiments, but that it have the full scope permitted by thelanguage of the following claims.

1. A valve structure for a sphincter in a body lumen, the valvestructure comprising: a tubular valve body having proximal and distalends, the valve body having an intermediate section which is between theproximal and distal ends, the valve body being sized for implanting inor around the sphincter such that the proximal end is upstream and thedistal end is downstream of the sphincter, the intermediate sectionbeing in crossing relation to the sphincter when the valve body isimplanted in or around the sphincter, the valve body having an innersurface and a lumen, the lumen having a transverse boundary which isdefined by the inner surface of the valve body, the inner surface whichis within the intermediate section having a cross-sectional area whichis smaller than a cross-sectional area of the inner surface whichcoincides with the proximal end to resist a flow through the lumen ofthe valve body from the proximal end to the intermediate section.
 2. Avalve structure according to claim 1, wherein the sphincter is definedby a pylorus, the body lumen being defined by a passage which isinternal to the pylorus, the valve body being sized for implanting in oraround the pylorus such that the proximal end is upstream and the distalend is downstream of the pylorus, the intermediate section being incrossing relation to the pylorus when the valve body is implanted in oraround the pylorus.
 3. A valve structure according to claim 1, andfurther comprising: a flow restrictor secured to the inner surface ofthe valve body to resist the flow through the lumen of the valve body.4. A valve structure according to claim 1, wherein the distal end has alarger cross-section than the intermediate section.
 5. A valve structureaccording to claim 1, and further comprising an elongate support membersecured to the valve body.
 6. A valve structure according to claim 1,wherein the valve body has an entry section between the intermediatesection and proximal end, the intermediate section being more flexibletransversely relative to the entry section.
 7. A valve structureaccording to claim 1, and further comprising an anchor structureattached to an outer surface of the valve body.
 8. A valve structureaccording to claim 7, wherein the anchor structure comprises a hook. 9.A valve structure according to claim 7, wherein the anchor structurecomprises a stake.
 10. A valve structure according to claim 3, whereinthe flow restrictor comprises one or more baffles which are secured tothe inner surface of the valve body.
 11. A valve structure according toclaim 10, wherein the baffles are longitudinally offset relative to thevalve body.
 12. A valve structure according to claim 11, wherein thebaffles are secured to sections of the inner surface of the valve bodywhich are transversely offset relative thereto.
 13. A valve structureaccording to claim 3, wherein the flow restrictor comprises a transversemembrane and one or more orifices formed therein.
 14. A valve structureaccording to claim 13, wherein the membrane has one or more sectionswhich are flexible longitudinally relative to the valve body.
 15. Avalve structure according to claim 13, wherein the one or more orificescomprise one or more slits.
 16. A valve structure according to claim 3,wherein the flow restrictor comprises an internal thread formed on theinner surface of the valve body.
 17. A valve structure according toclaim 16, wherein the internal thread has a sufficiently largetransverse dimension such that an internal edge of the internal threadhas longitudinal portions which transversely overlap one anotherrelative to the valve body.
 18. A method for implanting a valvestructure within a pylorus, said method comprising: providing a valvestructure including a tubular valve body having proximal and distalends, the valve body having an intermediate section which is between theproximal and distal ends, the valve body having an inner surface and alumen, the lumen having a transverse boundary which is defined by theinner surface of the valve body, the inner surface which is within theintermediate section having a cross-sectional area which is smaller thana cross-sectional area of the inner surface which coincides with theproximal end to resist a flow through the lumen of the valve body fromthe proximal end to the intermediate section; and inserting the distalend of the valve body in a downstream direction through a pylorus suchthat the proximal end is upstream of the pylorus and the distal end isdownstream of the pylorus, said inserting locating the intermediatesection in crossing relation to the pylorus.
 19. A method according toclaim 18, wherein the valve structure comprises an anchor structureattached to an outer surface of the valve body, the method comprisingimplanting the anchor structure in an inner surface of a stomach orduodenum which is adjacent to the pylorus.
 20. A method according toclaim 19, wherein the anchor structure comprises a hook, said implantingcomprising implanting the hook in the inner surface of the stomach orduodenum.
 21. A method according to claim 19, wherein the anchorstructure comprises a stake, said implanting comprising implanting thestake in the inner surface of the stomach or duodenum.
 22. A method forimplanting a valve structure within a pylorus, said method comprising:providing a valve structure including a tubular valve body havingproximal and distal ends, the valve body having an intermediate sectionwhich is between the proximal and distal ends, the valve body having aninner surface and a lumen, the lumen having a transverse boundary whichis defined by the inner surface of the valve body, the inner surfacewhich is within the intermediate section having a cross-sectional areawhich is smaller than a cross-sectional area of the inner surface whichcoincides with the proximal end to resist a flow through the lumen ofthe valve body from the proximal end to the intermediate section, thevalve body being inserted through a pylorus; and displacing the valvebody in an upstream direction relative to the pylorus to retract theintermediate section from within the pylorus and to dislodge the valvestructure therefrom.
 23. A method according to claim 22, wherein thevalve structure includes an anchor structure attached to an outersurface of the valve body, the anchor structure being implanted in aninner surface of a stomach or duodenum which is adjacent to the pylorus,the displacing further comprising displacing the valve body in anupstream direction relative to the pylorus to dislodge the anchorstructure from the inner surface of the stomach or duodenum, saiddisplacing being sufficient to retract the intermediate section fromwithin the pylorus and to dislodge the valve structure therefrom andfrom the inner surface of the stomach or duodenum.